LTE PHY Spec. Samsung ElectronicsJune 24, 2008Contents Downlink Spec. Downlink Structure: FDD, TDD Initial Access Cell Search (PSC, SSC, RS) System Information Receive (PBCH, PCFICH, PDCCH) Random Access Downlink data transmission: PHICH, PDSCH Uplink Spec. Uplink Structure Uplink slot structure Uplink physical channels and signals Physical uplink shared channel (PUSCH) Physical uplink control channel (PUCCH) Reference signal (RS) Physical random access channel (PRACH)1Downlink structureLTE L1 Specification23Frame Structure Frame structure Frame structure type 1 Applicable to FDD and half duplex FDD Each radio frame is long and consists of 20 slots of length , numbered from 0 to 19( seconds) Frame structure type 2 Applicable to only TDD Each radio frame consists of two half frame length each and each half frame consists of 8 slots of length and #0 #1 #2 #3 #19One slot, Tslot= 15360Ts=0.5 msOne radio frame, Tf= 307200Ts=10 ms#18One subframems 10307200sf= TTms 5.0T15360sslot=Tms 5153600sf= TTms 5.015360sslot= TT( )2048150001s=TFrame Structure Frame structure type 2(Cont.) Three special fields, DwPTS, GP, and UpPTS in subframe #1 and #6 Subframes 0 and 5 and DwPTS are always reserved for downlink transmission The lengths of DwPTS and UpPTS is given below subject to the total length of DwPTS, GP and UpPTS being equal to Supported configurations of uplink-downlink subframe allocation are specifiedms 107203s=TLengths of DwPTS/GP/UpPTSUplink-downlink allocations5Downlink Physical channels A set of Resource Elements carrying information originating from higher layers Physical Downlink Shared Channel, PDSCH Physical Broadcast Channel, PBCH Physical Multicast Channel, PMCH Physical Control Format Indicator Channel, PCFICH Physical Downlink Control Channel, PDCCH Physical Hybrid ARQ Indicator Channel, PHICH Physical signals A set of Resource Elements NOT carrying information originating from higher layers Reference signal Synchronization signal6Resource Grid The transmitted signal in each slot is described by a resource grid of subcarriers and OFDM symbols. The resource grid structureRBscDLRBNNDLsymbN10ms radio frame, Tf#1 #2 #3 #4 #5 #6 #7 #8 #9SubframeSlot, Tslot0.5 msec1msec#0Resource Block (RB)Resource element (k,l)l=0 l=NsymbDL-1SymbolSubcarrier15kHz#0 #1k = nPRB*NSCRBResource Grid Physical resource block parameters Number of symbols per slot Number of RBs per Channel bandwidth Ref. TS 36.104ConfigurationRB size (number of sub- carriers)Number of symbols per slotNormal CP (15kHz)127Extended CP15kHz67.5kHz24 3Channel bandwidth BWChannel MHz1.4 3 5 10 15 20FDD mode 6 15 25 50 75 10078Resource Grid In case of multi-antenna transmission, There is one resource grid defined per antenna port. An antenna port is defined by its associated reference signal. The set of antenna ports supported depends on the reference signal configuration in the cell: Cell-specific reference signals, associated with non-MBSFN transmission, support a configuration of one, two, or four antenna ports, i.e. the index , p, shall fulfil and p=0,p=0, 1, p=0, 1, 2, 3 , respectively. MBSFN reference signals, associated with MBSFN transmission, are transmitted on antenna port p=4. UE-specific reference signals, supported in frame structure type 2 only, are transmitted on antenna port p=5. Make sure that antenna port is not physical “Antenna”Resource Element Groups REGs (Resource element groups) Basic RE mapping unit for downlink control information Index pair of the resource element with the lowest index kin the group with all resource elements in the group having the same value of l 1st symbol of 1 slot Two REGs in PRB (k, l=0) with and 2nd symbol of 1 slot 1 or 2 antenna port case: 3 REGs in PRB (k, l=1) with, , 3 or 4 antenna port case: Same as 1st symbol of 1slot with l=1 3rd symbol of 1 slot Same as 1 or 2 antenna port case of 2nd symbol of 1st slot with l=2 Mapping of symbol quadruplet onto a REG5 ,.,1 ,0000+= kkkk 11 ,.,7 ,6000+= kkkk3 ,.,1 ,0000+= kkkk7 ,.,5 ,4000+= kkkk 11 ,.,9 ,8000+= kkkk)3(),2(),1(),( + izizizizz(i) 1 4 6 7 8 9 10 114 5 6 7 8 9 10 111 4 6 7 8 9 10 114 5 6 7 8 9 10 11Physical resource blockz(i+1)z(i+2) z(i+3)z(i) z(i+1) z(i+2) z(i+3)z(i) z(i+1) z(i+2) z(i+3)z(i) z(i+1) z(i+2) z(i+3)REGQuadruplet9Initial AccessLTE L1 Specification10Initial Access Initial access procedure for LTE has three steps. Cell Search System Information Receive Random Access 11Cell search Cell search Find a cell to connect and estimate frame timing Provide the primary and secondary synchronization signals on the downlink to assist Cell-specific sequences are inserted in synchronization signals Support 504 unique physical-layer identities; NIDcell(168 unique